Existing processes for the production of multi-modal polyethylene typically rely on two or more polymerization reactors operating at different reaction conditions. Generally, in a two-reactor in series systems, catalyst is fed only to the first reactor in the series so that the polymer particles eventually produced are of more homogeneous composition, i.e. so that all particles contain polymer produced in both reactors. In continuous reactions systems, however, there always exists some level of polymer bypass (i.e. from one reactor into the next) such that all polymer particles do not have the same residence time in each of the two reactors. This may result in formation of polymer gels and non-homogeneous particles which may be difficult to melt process. Additionally, matching production rates in two (or more) reactors may be complicated due to catalyst decay and may also lead to polymer inhomogeneity. Further, in order to provide a broad molecular weight distribution, the individual polymer components produced in each reactor are frequently made to have different molecular weight peaks, leading to a “valley” in the molecular weight distribution of the final overall polymer product.